Oxygen-air diluter for breathing apparatus



United States Patent Inventor Herbert F. Veit Fullerton, California Appl. No. 685,657

Filed Nov. 24, 1967 Patented Sept. 1, 1970 Assignee Rohertshaw Controls Company Richmond, Virginia a corporation of Delaware OXYGEN-AIR DILUTER FOR BREATHING APPARATUS 7 Claims, 3 Drawing Figs.

U.S. Cl 137/81, 137/114,137/489,137/512.15

Int. Cl. A62b 9/00 Field of Search l37/63R,

Primary ExaminerWilliam F. O'Dea Assistant Examiner-Richard Gerard Atlorney- Auzville Jackson, Jr., Robert L. Marben and Christen, Sabol, Ql3rien and Caldwell ABSTRACT: An oxygen-air diluter for breathing apparatus wherein a single valve member controls the inlet oxygen flow and the outlet oxygen flow to the air diluter portion of the system.

Patented Sept. 1, 1970 ATTORNEYS OXYGEN-AIR DILUTER FOR BREATHING APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to breathing apparatus and in particular, to an oxygen-air diluter of the demand type utilized in high altitude and space flights.

2. Description of the Prior Art Conventional type of oxygen air systems presently used in high altitude aircraft or spacecraft provide for dilution of oxygen and air in a varying proportion in accordance with atmospheric pressure variations. Recent developments in such systems, as shown in the copending application of August Oroza, Ser. Number 413,801 filed November 25, I964, utilizes a variable nozzle for the oxygen flow with the variation being a function of the pressure of the oxygen flow. While the Oroza system performs satisfactorily, it requires the use of two separate oxygen control valves, viz., the oxygen demand inlet valve and the oxygen variable nozzle valve.

SUMMARY OF THE INVENTION In accordance with the present invention, the need for two separate oxygen control valves is eliminated in an oxygen-air diluter for breathing apparatus.

It is, therefore, an object of the present invention to control the flow of oxygen in an oxygen-air diluter for breathing apparatus by a single valve member as a function of the demand from the breathing apparatus.

The present invention has another object in that a venturi throat is utilized to increase the efficiency of the system.

In practicing the present invention, breathing apparatus is provided in a oxygen-air diluter including a casing having an oxygen inlet adapted for connection to an oxygen source, an air inlet adapted for comunication with the atmosphere, an air flow chamber communicating with the air inlet, and an outlet adapted for connection to the breathing apparatus, oxygen regulating means movable between regulating positions in response to demand at the outlet, a venturi throat disposed between said air flow chamber and the outlet, variable nozzle means disposed to deliver a flow of oxygen with a jet velocity into the venturi throat whereby a flow of oxygen is induced thereinto, and the variable nozzle means including a movable valvemember operatively connected to the oxygen regulating means whereby the valve member controls both inlet oxygen flow and oxygen flow to the venturi throat.

Other objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross-section of a breathing control device embodying the present invention; FIG. 2 is a cross-section similar to FIG. I but with the control elements shown in an open position; and FIG. 3 is an exploded perspective of a detail of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT As is illustrated in FIG. I of the drawing, the present invention is embodied in a breathing control device in the form ofa casing, indicated generally at 10, having an inlet 12 adapted to be connected to a source of oxygen (not shown) and an outlet I4 adapted to be connected to a breathing device (not shown) such as a helmet or face mask. The inlet 12 communicates with an oxygen inlet chamber 16, one end of which is defined by conical valve seat 18 aligned with the flared inlet portion 20 of a venturi throat portion 22 leading to the outlet 14. A conica'lly shaped valve member 24 cooperates with the valve seat 18 and has a valve stem attached to a flexible diaphragm 26 closing the opposite end of inlet chamber 16.

An aperture 28 in the diaphragm 26 establishes communication between the inlet chamber 16 and a bleed chamber 30 having a pilot orifice 32 which is controlled by a flapper valve 34 pivotally mounted intermediate its ends to a wall of a suction chamber 36. An actuating button 38 for the flapper valve 34 is reciprocably mounted in a guide bushing 40 centrally located in the suction chamber 36 by means of an apertured baffle or dampening plate 42. The actuating button 38 is fixed to the center of a flexible diaphragm 44 which defines a movable wall of the suction chamber 36. The chamber 36 is a demand sensing chamber and has a demand sensing port 45 establishing communication between the casing outlet 14 and the chamber 36.

The upper side of the diaphragm 44 defines the movable wall of an atmospheric chamber 46 which houses an aneroid bellows 47. As is shown in FIG. 1, a movable end of the bellows 47 abuts the center of diaphragm 44 on the side opposite the actuating button 38; the opposite end of bellows 47 is centrally fixed to an adjusting screw 48. The adjusting screw 48 is threaded through the end wall of casing 10 that defines the atmospheric chamber 46 and an aperture 49 through such end wall establishes communication between the chamber 46 and the atmosphere. The aneroid bellows 47 changes the reference of the oxygen regulator to predetermined parameters; increasing altitudes cause the bellows 47 to expand and contract the diaphragm 44, applying a force that increases the regulated pressures above the ambient pressures in proportion to altitude; decreasing altitudes cause the aneroid bellows 47 to contract with resultant lower regulated pressures.

The mixture chamber 20 communicates with an air flow chamber 50 having an aneroid bellows 52 fixedly attached at one end to an adjustment screw 54 that is adjustably threaded into a wall of the air flow chamber 50. The opposite end of bellows 52 has a flat surface to limit the movement of a valve disc 56 which is centrally attached to a spider plate 58. The valve disc 56 and spider plate 58 are mounted as a unit with the spider plate being press fitted into the edge of a cupshaped housing 60 and with the periphery of the valve disc 56 engaging an annular lip flange 62 on the housing 60. The valve disc 56 defines a one-way check valve and is made of suitable flexible material so that its periphery is movable between the flange 62 and the flat end surface of the bellows 52. A plurality of slots 64 spaced around the cylindrical wall of the housing 60 permit a flow of air into the housing and are controlled by a manually movable closure cap 66. The closure cap 66 is slidably attached to the housing 60 by means of a central stud 68 extending through an aligned opening in the housing and having a flattened end to limit axial outward movement of the closure cap 66.

In the following description of a sequence of operation of the present invention, it is to be noted that the flow of oxygen is controlled by demand and thus varied with inhalation and exhalation at the face mask of the user. Thus, the flow of oxygen is zero at the start of inhalation, rises to a controlled maximum during inhalation, then decreases to zero and remains zero during exhalation.

FIG. 1 represents the relative positions of the control elements when there is no demand for oxygen and with the air inlet control manually closed. While the air inlet control valve (elements 5268) may be manually closed so that percent oxygen would be supplied, the usual arrangement is to manually open the air inlet ports 64 by axial outward move: ment of the closure cap 66; then the amount of air entering the system is a function of atmospheric pressure or altitude because the bellows 52 automatically controls the air inlet valve 56. Of course, at higher altitudes, the pressure on the exterior of the bellows 52 is lessened so that the bellows 52 expands and maintains the air inlet valve 56 completely closed. Thus, under conditions of altitude where I00 percent oxygen is needed, the aneroid bellows 52 expands to prevent any air flow into the system.

Manual opening of the closure cap 66 places the device in condition to function as an oxygen diluter system wherein the correct ratio of oxygen and air is automatically proportioned for breathing purposes. The diluter demand regulator thus conserves oxygen, permitting either longer duration aircraft and space flights or minimizing the oxygen supply that must be carried on flights of normal duration. Accordingly, when the demand for oxygen occurs as by inhalation at the face mask, there is a decrease in pressure under the diaphragm 42 causing it to flex downward in proportion to the suction applied as sensed through the sensing port 45. As is illustrated in FIG. 2, downward movement of the diaphragm 42 and its attached actuating button 38 causes clockwise pivoting of the flapper valve 34 which thus opens the orifice 32 in proportion to the suction applied to the suction chamber 36. The pressure in bleed chamber 30 decays at a faster rate than it can be replenished because the orifice 32 is larger than the aperture 28 in the oxygen regulator diaphragm 26. The pressure differential between inlet chamber 16 and the bleed chamber 30 has caused the diaphragm 26 to flex upwardly whereby the attached oxygen control valve 24 is opened to permit oxygen flow in proportion to its opened position. The flow of oxygen past the valve seat 18 is in direct proportion to the suction applied by the user of the face mask upon the underside of the diaphragm 44 through the sensing line 45. Conversely, a decrease in suction results in a diminishing rate of flow of the oxygen.

The suction created at the outlet 14 by inhalation at the face mask is also reflected in the air flow chamber 50 causing the air inlet valve disc 56 to flex to an open position against the bellows 52. Air is now permitted to flow through the ports 64 and past the valve disc 56 into the air flow chamber, whence it is mixed with the oxygen in the mixture chamber 20. The oxygen is diluted with the air when the oxygen flow from the valve seat 18 creates a lowering of the static pressure in the venturi throat 22 to a level less than the ambient pressure. The ambient air, seeking a lower pressure level flows from the air chamber 50 whence it is induced into the jet stream of the oxygen flow entering the throat inlet 20. In order to attain the lowest static pressure level, it is necessary to maintain the oxygen flow at a high level of kinetic energy. Neglecting heat losses, the total energy level of the oxygen consists of the sum of the static pressure energy and the kinetic energy.

In accordance with the present invention, a low static pressure energy is assured by maintaining a high kinetic energy level at all flow condition of the oxygen. High oxygen inlet pressure and a low regulated pressure assure sonic velocity at the nozzle throat 22 with each inhalation at the face mask. Because the kinetic energy varies directly with the square of the velocity, i.e., K .E. V /2g, it is apparent that sonic flow of oxygen creates an optimum condition for assuring a minimum static pressure at the venturi throat 22. This provides a maximum differential pressure between the ambient air and the static pressure for maximum air intake.

With the valve seat 18 and valve member 24 defining a variable nozzle control being in alignment with the throat inlet 20, the jet velocity of the oxygen flow entrains air from the air chamber 50 for delivery to the venturi throat 22 whereby the oxygen-air mixture itself is subject to venturi action of the venturi throat 22. Since the valve seat 18 is located adjacent the venturi inlet 20, the main valve 24 provides a maximum kinetic energy level for direct dilution of oxygen with air at that flow point where there is a minimum static pressure, i.e., in the venturi throat 22. Accordingly, there is no need for supplementary dynamic flow devices as would be required in conventional systems.

Inasmuch as the preferred embodiment of the present invention is subject to many modifications, variations and changes in details, it is intended that all matter contained in the foregoing description or shown on the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

lclaim:

ll. An oxygen-air diluter for breathing apparatus comprismg:

a casing having an oxygen inlet adapted for connection to an oxygen source;

an air inlet adapted for communication with the at- P here; an air ow chamber communicating with said air inlet, and

an outlet adapted for connection to the breathing apparatus;

oxygen regulating means in said casing movable between regulating positions in response to demand at said outlet;

a venturi throat disposed between said air flow chamber and said outlet;

variable nozzle means including a fixed valve seat and a movable valve member axially disposed to deliver a flow of oxygen with a jet velocity into said venturi throat whereby a flow of air is induced thereinto;

said movable valve member being operatively connected to said oxygen regulating means whereby said movable valve member controls both inlet oxygen flow and oxygen flow to said venturi throat; and

air control valve means in said air flow chamber including a flexible valve disc movable between opened and closed positions in accordance with the jet velocity of the oxygen flow into said venturi throat and an aneroid bellows adjustably carried by said casing to define the opening limits of said valve disc in response to atmospheric pressure.

2. The invention as recited in claim 1 wherein said oxygen regulating means includes a differential pressure diaphragm operatively connected to said movable valve member for imparting movement thereto and having a bleed port through a portion of said diaphragm whereby both sides thereof are subject to oxygen inlet pressure.

3. The invention as recited in claim 2 wherein said oxygen regulating means includes bleed valve means and a diaphragm operator therefor whereby one side of said differential pressure diaphragm may be at a lower pressure than the oxygen inlet pressure,

4. The invention as recited in claim 3 wherein said bleed valve means bleeds the one side of said differential pressure diaphragm at a faster rate than can be replenished by said bleed port.

5. The invention as recited in claim 4 wherein said bleed valve means comprises a pivoted flapper valve having one end engageable by said diaphragm operator.

6. The invention as recited in claim 5 wherein said diaphragm operator has one side responsive to demand at said outlet whereby the rate of oxygen bled past said flapper valve is proportional to the demand.

7. The invention as recited in claim 6 wherein said diaphragm operator has an opposite side responsive to an aneroid bellows whereby the rate of oxygen bled past said flapper valve is influenced by atmospheric pressure. 

